Burner control device for a water heater



. Patent 3,402,ss1.. i BURNER CONTROLDEVICE FORA ,WATERHEATER h les' l ys l t. Lm [Mo-f ss E e ectri'cCo.,"St.L0uis, Mo., a corporation ofMissouri Filed June16,"196 6,"Ser.' No; 558,012

4"Cl'aims;(Cl.'236;21)

xThisinvention relates to automatic fuel .flow control devices'for waterheater gas burners which have valve and temperatureresponsive'valveactuator means for controlling the flow of gas to theburner in accordance with heat requirements to maintain a selected Watertemperature and an electromagnetically operated cutoff valvedependentupon'e'lectrical energy generated by a pilot burner heatedthermocouple to hold it open; and it particularly concerns theprovision, .construction,--and disposition within the water tank of anormally closed, temperature responsive switch which controls thethermocouple, electromagnetic, cutolf valve circuit and. which opens inresponse to a predetermined high water temperature to de-energize theelectromagnetic cutoff valve and effect its closing.

.An object of the invention is to.provide a fuel flow control device forwater heater gas burners having an electromagnetically operated cutoffvalve and an energizing circuit therefor including asa. power source athermocouple heated by a pilot burner flame, in which a normally closed.temperature responsive switch disposed in good heat. transferrelationship, with the water being heated isincluded in. the energizingcircuit and is .operative in response to. a predeterminedhigh watertemperature to open, therebyto de-energize .the .electromagneticallyoperated-cutoff valve.

,1 Afurtherobject is to ,providemeans encapsulating and supporting atemperature responsive switch within a water heater tank in good heattransfer relationship with the water being heated. i

Other objects and advantages will appear from the following .descriptionand accompanying drawing.

- In the drawing: M I

FIG. 1 is across-sectional view,-.With parts shown in full, .of acontroldevice forwater-heater gas burners constructed, in accordance with thepresent invention and shown in association .with, awater, heater tank;

FIG." 2 is. an enlarged fragmentary, cross-sectional view taken on line2- 2 of. F,IG. 1; 1

F IG..3.is alongitudinalcrossrsectional view of the electromagneticallyoperated cutoff valve and its circuit connections;

FIG. 4 is a side elevational View of the temperature responsive switch;1 'FIGUS is across-sectional view-of the temperature responsive switchtaken on line 5-5 =of FIG. 4; and

FIG, 6 is an enlarged cross-sectional view taken on line 66ofFIG. 1. .2

Referring to the drawing, the, fuelflow control device comprises avalvebody 1 0 h'avingfront and rear cover members 12 and 14,respectively, attached to the body "by screws 16. The body 1Q' isprovided with an inlet passage 18, a. cutoff .valve'- chambe"r"20, amain valve chamber 22, and a main burner fuel supply outlet 24. Atapered bore 26;and*anlaxially aligned cylindrical bore 28 extendinwardly from opposite sides of the body 10 and intersect the cutoffValve chamber 20. The tapered bore 26 receives a hollow, tapered,rotatable plug cock 30, the open inner end of which extends into cutoffvalve chamber 20 and forms an annular valve seat 32. The cylindricalbore 28 receives an electromagnetic cutoff valve assembly, generallyindicated at 34, which includes a poppet valve 36 biased against valveseat 32 by a spring 13. An operating rod 11 axially slidable in plugcock 30 ice and having an external hand knob 17 is arranged to engagecutoff valve 36 and move it openward when knob 17; is pushed inwardly.The operating rod 11 and knob 17 are biased outwardly by a spring ,19.

The hollow plug cock 30 is provided with a circumfer entially extendingslot in the wall thereof forming a pilot burner port 38 which permitsflow from the interior of the plug cock to. a pilot burner outlet.passage 40 from whence the fuel is conducted to a pilot burner 43through a conduit 41. The plug cock 30 is also provided with a circularmain port 42 in the wall thereof which, when in registry with a bodypassage 44, permits fuel flow from the interior of the hollow plug cockto the main valve chamber 22. The circumferentially extending pilot port38 permits rotatable positioning of the plug cock so as to permit flowto the pilot outlet 40 only, or so as to permit flow to the pilot outlet40 and main valve chamber 22 simultaneously. A main poppet valve 46biased in a closed position on an annular seat 48 by a spring 50controls the flow from main valve chamber 22 to the main burner outletpassage 24. The main valve 46 has a stem 52 attached at one end to thevalve and its opposite end is arranged to *be engaged under certainconditions by the central portion of a thin, circular, concave-convex,flexible metal disc 54. The disc 54 has a normal free form, as shown inFIG. 1, in which it is concave with respect to the adjacent end of valvestem 52. The disc 54 is poised between a fixed, annular, knife edge 56,which engages the disc on its concave side very near its peripheraledge, and an annular knife edge 58 of slightly smaller diameter formedon the inner face of an axially movable member 60, which engages thedisc on its convex side. A slight inward movement of member 60 causesdisc 54 to pass through a planar shape to an opposite concavo-convexform with a snap action to engage the adjacent end of valve stem 52 andopen the valve 46.

The outer face of movable member 60 is provided with a hemisphericalboss 62 engaged by the free end of a lever 64, the lever 64 beingpivoted at its other end on the ballshaped end 66 of a threadedlyadjustable rod 68. The rod 68 is provided with a hand knob 70 on itsexteriorly projecting end. The rear body cover member 14 is providedwith an integrally formed, outwardly extending, cylindrical, hollow boss72 having an exteriorly threaded outer end portion threadedly engaged inan internally threaded bushing 74 welded into an aperture in the wall ofa water heater tank, shown fragmentarily at 70 in FIG. 1.

The cylindrical hollow boss 72 has a circular concentric bore 76extending inwardly from its outerend to a square bottom 78. Extendinginwardly from the bottom 78 of bore 76 and through the boss 72 to theinterior of the body is an eccentrically positioned bore 80 and acrescent-shaped passage '82 concentric with the bore 80. The bore 80 isthreaded to receive the reduced diameter end portion 84 of a tube 85.The tube 85 and a concentric rod 86 of a lower thermal expansion ratethan the tube form a conventional rod and tube, differential expansionthermostat,'the operation and construction of which is well known in theart. The rod 86 extends inwardly beyond the inner end of tube 85 andengages the lever 64 at an intermediate point therealong. The rod 86 andtube 84 extend outwardly from boss 72 into the water tank.

An elongated tube 88 having a closed outer end and an open inner end isarranged closely alongside and coextends with tube 84 into the watertank. The tube 88 'has a crescent form, cross-sectional configuration,as shown in FIG. 2, and is provided with a circular flange 90 at itsinner open end, which flange lies flat against the square bottom 78 ofbore 80 and fits the bore 80. The tube 88 is preferably constructed ofcopper, and

is thin walled, and is aligned with the crescent-shaped passage 82extending through the base portion boss 72. The flange 90 is providedwith a circular perforation 92, see FIG. 2, which receives the reduceddiameter threaded portion 84 of tube 85, and the flange 90 is clampedagainst the bottom 78 of bore 76 by the shoulder for-med on tube 85 bythe reduced diameter portion 84.

Positioned in the tube 88 near its outer closed end is a normally closedtemperature responsive switch generally indicated at 94. Referring toFIGS. 4 and 5, the switch 94 comprises a flat base member 95 ofdielectric material. A first long, fiat strip conductor 98 is attachedat -a point near its outer end to base member 95 by a solid rivet 96 andis further attached to base member 95 at a point yet nearer its outerend by a hollow rivet 97. A second, long, flat co-extending stripconductor 99 having its outer end portion overlying conductor 98 andseparated therefrom by an insulating strip 100 is attached to the basenear its outer end by the solid rivet 96 only. The conductor strip 98carries a stationary contact 102 at its extreme outer end, and conductorstrip 99 carries a movable contact 104 at its extreme outer end whichcooperates with stationary contact 102. The outer free end portion ofconductor strip 99 is flexible and has a free form which normally spacesthe movable contact 104 from contact 102 in open circuit position.However, a thin, circular, concavo-convex, bimetal disc 106, with itsconcave side facing the base member, overlies the end portion ofconductor strip 99 and with a portion of its peripheral edge engagingthe outer end of conductor strip 99 presses movable contact 104 againststationary contact 102 in closed circuit position under normal watertemperature conditions. When the bimetal disc 106 is heated by theambient water to a predetermined temperature, it snaps through a planarshape to an opposite concave-convex form and permits the free endportion of conductor strip 99 to assume its free form and separate themovable contact 104 from stationary contact 102.

The hollow rivet 97 is internally threaded and the bimetal disc 106 iscentrally perforated and receives an adjustment screw 108 threadedlyengaged in hollow rivet 97. The screw 108 has a head 110 at one endthereof bearing against the convex side of bimetal disc 106 and a screwdriver slot at its other end. As the adjusting screw 108 is turnedinward so as to increase the pressure on the convex side of bimetal disc106, the temperature setting at which the disc will snap over center isreduced.

The conductor strips 98 and 99 co-extend inwardly from switch 94 inspaced relationship through tube 88 and into crescent-shaped passage 82in boss 72. The inner ends of conductor strips 98 and 99 are fixed inspaced relationship in passage 82 by a mass of relatively rigiddielectric material which is preferably a synthetic thermoplastic orthermosetting material. The conductor strip 98 is connected at its innerend, as by soldering, to an insulated lead 112 which extends from boss72 to the electromagnetic cutoif valve device 34, and the inner endportion of conductor strip 99 lies against and is electrically groundedto the boss 72. The circular bore 76 in stud 72 is also at leastpartially filled with the material 110 which forms a liquid seal toprevent any passage of liquid from the water tank through hollow boss72. It is to be understood that the flat conductor strips 98 and 99 aresufiiciently rigid to support the switch 94 in position in tube 88.

Referring to FIG. 3, the electromagnetic cutoff valve assembly comprisesa cylindrical casing 114 which is connected at one end to a terminalplug 116. The other end of casing 114 slidably supports a valve stem 118which extends exteriorly and interiorly of the casing. Valve stem 118carries the valve 36 on its exteriorly projecting end and an armature onits interior end. The terminal plug 116 has a threaded bore 117 and asmaller through bore 121 resulting in an internal shoulder 119. Theterminal plug 116 is also provided with an enlarged diameter, threaded,flange portion which is threadedly engaged in the threaded entranceportion 122 of cylindrical bore 28. The casing 114 houses a U-shapedmagnet core 124 having a winding 126 surrounding its parallel legportions 128. A conductive rivet 132 extends through a bore in the legconnecting portion of the magnet core and-through the bore 121 interminal plug 116 and rigidly connects the core to the terminal plugmechanically. The inner end of conductive rivet 13-2 is connected to oneend of winding 26 at 131. A circular, molded, dielectric member 134 isinterposed between the casing 114 and terminal plug 116, and the member134 includes encased therein a conductor 136 having one end extendinginto casing 114 and being connected to the other end of winding 126 andhaving its other end extending exteriorly of body member 10 and beingconnected to lead 112.

A thermocouple junction encased in casing 138 is disposed with relationto pilot burner 43 so as to be impinged by the flame thereof. Coaxialtube and wire conductors 140 and 141, respectively, lead from thethermocouple junction to terminal plug 116. The end portions of tube andwire conductors 140 and 141 pass through a hollow nut 143 which isthreadedly engaged in the threaded bore 117. The tube conductor 140 hasa flared end which bears against the end of nut 143, and the wireconductor 141 has an enlarged diameter contact element 142 at its endwhich bears against the inner end of conductive rivet 132. An insulatingwasher is interposed between the fiared end of conductor tube 140 andthe contact element 142. Dielectric grommets insulate the conductiverivet 132 from the terminal plug 116 and the portion 130 of the magnetcore.

The thermocouple electromagnet circuit may be traced from the end of astrip conductor 99 grounded to metal cover 14 through the conductor 99,through normally closed switch contacts 104 and 102, through stripconductor 98, lead 112 and conductor 136 to one end of winding 126,through winding 126, rivet 132, and wire conductor 141 to thethermocouple junction in casing 138, and from the thermocouple junctionthrough tube conductor 140 to hollow nut 143, and terminal plug 116which is grounded to cover member 14.

Operation When it is desired to start burner operation, the plug valve30 is rotated to a pilot position which will permit fuel to flow fromthe hollow portion of plug valve 30 to the pilot burner 43 through thecircumferentially slotted port 38, but will not permit flow throughcircular port 42 to chamber 22. The knob 17 is then pushed inward toopen cutoff valve 36 and to move armature 15 into contact with the endsof magnet core legs 128. The pilot burner is then ignited by anysuitable means and the knob 17 is held inward until electrical energy isgenerated at the thermocouple junction and is sufficient to energizewinding 126 and hold the armature 15 against core 124 and the cutoffvalve 36 open. Thereafter, the plug cock 30 is rotated to an on positionin which fuel flows through port 42 to chamber 22 as well as throughslotted port 38 to the pilot burner.

If the water temperature as sensed by the tube 85 of the rod and tubethermostat is less than that selected by the positioning of knob 70, thetube will be in such contracted position as to cause rod 86, throughlever 64 and member 60, to open main valve 46. Fuel will thereby bepermitted to flow to the main burner outlet 24 and to a main burner (notshown) where it is ignited by the pilot burner. When the water reachesthe selected temperature due to operation of the main burner lengthwiseexpansion of tube 85 will cause the withdrawal of rod 86 and permit discelement 54 to return to its normal free position, as shown, and willpermit valve 46 to close under the bias of spring 50. Under normalconditions, the main valve 46 will now be operated between open andclosed positions to supply fuel to the main burner as required tomaintain a selected Water temperature.

If, however, for any reason, the temperature of the water in the watertank exceeds that which has been predetermined as a safe upper limit,the bimetal disc 106 will warp and snap to an opposite concavo-convexform than shown in FIG. 5, and contacts 102 and 104 will ,separate,thereby breaking the thermocouple electromagnet circuit. As a result thewinding 126 will be deenergized and spring 13 will return cutoff valve36 to a closed position, thereby cutting off the flow of fuel to bothpilot and main burners.

The foregoing description is intended to be illustrative and notlimiting, the scope of the invention being set forth in the appendedclaims.

I claim:

1. In a device of the kind described having a valve body, an externallythreaded mounting boss projecting from said body, a main valve in saidbody, a rod and tube type thermostat operatively connected to said mainvalve, a biased closed cutoff valve in said body, electromagnetic meanswhich when energized holds said cutoff valve open, and a circuitincluding an electrical power source for energizing said electromagneticmeans; the improvement which consists in providing said mounting bosswith a relatively large longitudinal bore extending inwardly from itsouter end and terminating in a flat bottom and in providing tworelatively small longitudinal passages extending inwardly from said borebottom to the interior of said valve body, one of which passages isinternally threaded; in providing a relatively thin-walled encapsulatingtube of good heat conductive material having a closed end, an open end,and a circular off-center flange at its open end, which flange fits saidrelatively large bore, is entered into said bore, and lies flat againstsaid bore bottom, and said tube being aligned with the other of saidrelatively small passages and extending outwardly from said mountingboss, said off-center flange having a perforation therein aligned withsaid one relatively small passage; in providing the tube of the rod andtube thermostat with a reduced diameter, externally threaded, inner endportion passing through said flange perforation in fitting relationshipand being threadedly engaged in said one relatively small passage,thereby clamping said flange against said bore bottom; in providing anormally closed thermostatic switch responsive to open at a relativelyhigh temperature and in supporting said switch with its thermostaticactuator in said encapsulated tube near the outer closed end thereof;and in providing circuit connections connecting said thermostatic switchin series with said electromagnetic means and said power source in saidenergizing circuit.

2. A device as set forth in claim 1 in which said encapsulating tube hasa generally crescent form, crosssectional configuration with its majorarcuate walls having their centers of curvature substantially on theaxis of said rod and tube thermostat.

3. A device as set forth in claim 1 in which said circuit connectionsinclude a pair of spaced conductors coextending longitudinally in saidencapsulating tube and being attached at their outer ends to saidthermostatic switch and at their inner ends to said valve body and beingof sufiicient rigidity to support said thermostatic switch in a fixedposition in the outer end of said encapsulating tube.

4. A device as set forth in claim 3 in which the inner ends of saidconductors extend into said other relatively small passage in spacedrelationship, in which said other relatively small passage issubstantially filled with a relatively rigid dielectric cementingmaterial, thereby to support the inner ends of said conductors and toseal said passage, and in which said relatively large circular bore isat least partially filled with a fluid-sealing cementing material.

References Cited UNITED STATES PATENTS 3,291,390 12/1966 Solomon 236-213,320,388 5/1967 Kreuter 200-437 EDWARD 1. MICHAEL, Primary Examiner.

1. IN A DEVICE OF THE KIND DESCRIBED HAVING A VALVE BODY, AN EXTERNALLYTHREADED MOUNTING BOSS PROJECTING FROM SAID BODY, A MAIN VALVE IN SAIDBODY, A ROD AND TUBE TYPE THERMOSTAT OPERATIVELY CONNECTED TO SAID MAINVALVE, A BIASED CLOSED CUTOFF VALVE IN SAID BODY, ELECTROMAGNETIC MEANSWHICH WHEN ENERGIZED HOLDS SAID CUTOFF VALVE OPEN, AND A CIRCUITINCLUDING AN ELECTRICAL POWER SOURCE FOR ENERGIZING SAID ELECTROMAGNETICMEANS; THE IMPROVEMENT WHICH CONSISTS IN PROVIDING SAID MOUNTING BOSSWITH A RELATIVELY LARGE LONGITUDINAL BORE EXTENDING INWARDLY FROM ITSOUTER END AND TERMINATING IN A FLAT BOTTOM AND IN PROVIDING TWORELATIVELY SMALL LONGITUDINAL PASSAGES EXTENDING INWARDLY FROM SAID BOREBOTTOM TO THE INTERIOR OF SAID VALVE BODY, ONE OF WHICH PASSAGES ISINTERNALLY THREADED; IN PROVIDING A RELATIVELY THIN-WALLED ENCAPSULATINGTUBE OF GOOD HEAT CONDUCTIVE MATERIAL HAVING A CLOSED END, AN OPEN END,AND A CIRCULAR OFF-CENTER FLANGE AT ITS OPEN END, WHICH FLANGE FITS SAIDRELATIVELY LARGE BORE, IS ENTERED INTO SAID BORE, AND LIES FLAT AGAINSTSAID BORE BOTTOM, AND SAID TUBE BEING ALIGNED WITH THE OTHER OF SAIDRELATIVELY SMALL PASSAGES AND EXTENDING OUTWARDLY FROM SAID MOUNTINGBOSS, SAID OFF-CENTER FLANGE HAVING A PERFORATION THEREIN ALIGNED WITHSAID ONE RELATIVELY SMALL PASSAGE; IN PROVIDING THE TUBE OF THE ROD ANDTUBE THERMOSTAT WITH A REDUCED DIAMETER, EXTERNALLY THREADED, INNER ENDPORTION PASSING THROUGH SAID FLANGE PERFORATION IN FITTING RELATIONSHIPAND BEING THREADEDLY ENGAGED IN SAID ONE RELATIVELY SMALL PASSAGE,THEREBY CLAMPING SAID FLANGE AGAINST SAID BORE BOTTOM; IN PROVIDING ANORMALLY CLOSED THERMOSTATIC SWITCH RESPONSIVE TO OPEN AT A RELATIVELYHIGH TEMPERATURE AND IN SUPPORTING SAID SWITCH WITH ITS THERMOSTATICACTUATOR IN SAID ENCAPSULATED TUBE NEAR THE OUTER CLOSED END THEREOF;AND IN PROVIDING CIRCUIT CONNECTIONS CONNECTING SAID THEREMOSTATICSWITCH IN SERIES WITH SAID ELECTROMAGNETIC MEANS AND SAID POWER SOURCEIN SAID ENERGIZING CIRCUIT.